Method and apparatus for fabricating an anti-fatigue mat employing multiple durometer layers

ABSTRACT

A method and apparatus are disclosed for fabricating an anti-fatigue mat that employs a layer of resilient gel material that exhibits a first durometer. The method employs a frame assembly that receives a flexible support sheet. The frame assembly includes an aperture that receives a layer of heated liquid gel which cools to form the layer of resilient gel material exhibiting the first durometer. In one embodiment, a barrier layer exhibiting a second durometer is situated on the gel layer that exhibits the first durometer. In one embodiment, the barrier layer prevents the flow of oils from the gel layer to a flexible base sheet disposed on the barrier layer. In another embodiment, the flexible base sheet may exhibit a second durometer. In either embodiment, the layers exhibiting the first and second durometer cooperate to influence the feel of the mat to the user.

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

This patent application is a continuation-in-part of, and claimspriority to, the U.S. patent application entitled “Method and ApparatusFor Fabricating An Anti-Fatigue Mat”, inventor Robert L. McMahan, Ser.No. 11/537,648, filed 09-30-2006, that is assigned to the same Assigneeas the subject patent application, the disclosure of which isincorporated herein by reference in its entirety.

TECHNICAL FIELD OF THE INVENTION

The disclosures herein relate generally to mats and more particularly tomethodology and apparatus for manufacturing resilient floor mats forreducing user fatigue.

BACKGROUND

Floor mats have been used for years to provide a cushion for the personstanding on the mat. However, fatigue can still result when a personstands on a mat for an extended period of time. Persons who workstanding up most of the day, such as cashiers, assembly line operators,people in home or commercial kitchens and many others still experiencefatigue after standing on a conventional mat for long periods of time.Often floor mats are provided with non-slip surfaces to lessen slippageand to thus promote safety.

Mats of resilient foam are known to reduce user fatigue. Unfortunatelyhowever, foam mats have the disadvantage of becoming brittle over time.Conventional foam mats lose their properties as air cells in the matcompress. Moreover, conventional foam mats collect moisture over time.This condition can promote the growth of bacteria and fungus. Theseundesirable characteristics result in foam mats becoming unsuitable foruse as they become older.

A mat containing gel sandwiched between various cover layers may addressthese problems. For example, my U.S. Pat. No. 6,851,141 discloses aresilient mat, one embodiment of which includes a resilient gel innerlayer surrounded by a support ring to which an upper cover member and alower cover member are attached. However, manufacturing such gel-basedmats can be difficult. For example, difficulties can be encountered inadhering the upper cover member to the lower cover member. Moreover,undesired wrinkling of the cover members may also be experienced duringthe manufacture of a gel-based mat. Undesired wrinkling or creasing mayalso occur when a gel-based mat is stored for shipping in a rolled-upposition for an extended period of time and then later unrolled by theuser prior to use.

What is needed is a method of manufacturing a gel-based mat thataddresses one or more of the above described problems.

SUMMARY

Accordingly, in one embodiment, a method is disclosed for fabricating ananti-fatigue mat. The method includes positioning a first flexiblesupport sheet on a first frame member. The method also includespositioning a second frame member on the first flexible support sheet,the second frame member including an aperture configured to acceptheated liquid gel therein. The method further includes dispensing theliquid gel into the aperture in the second frame member so that theliquid gel covers a surface of the first flexible support sheet exposedby the aperture, the gel exhibiting a first predetermined durometer whencooled. The method still further includes positioning a barrier layer onthe second frame member and covering the liquid gel, the barrier layerexhibiting a second predetermined durometer. The method also includescooling the liquid gel to form a gel layer exhibiting the firstpredetermined durometer.

In another embodiment, an anti-fatigue mat is disclosed that includes afirst flexible sheet. The mat also includes a resilient gel layersituated on the first flexible sheet and exhibiting a firstpredetermined durometer. The mat further includes a flexible barrierlayer situated on the resilient gel layer, the flexible barrier layeradhering to the resilient gel layer, the flexible barrier layerexhibiting a second predetermined durometer different from the firstpredetermined durometer of the resilient gel layer. The mat stillfurther includes a second flexible sheet situated on the flexiblebarrier layer, the flexible barrier layer being moveable with respect tothe second flexible sheet.

In yet another embodiment, an anti-fatigue mat is disclosed thatincludes a first flexible sheet. A resilient gel layer is situated onthe first flexible sheet and exhibits a first predetermined durometer.The mat also includes a flexible barrier layer situated on the resilientgel layer, the flexible barrier layer adhering to the resilient gellayer. The mat further includes a second flexible sheet situated on theflexible barrier sheet, the flexible barrier sheet being moveable withrespect to the second flexible sheet, the second flexible sheetexhibiting a second predetermined durometer different from the firstpredetermined durometer of the resilient gel layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The appended drawings illustrate only exemplary embodiments of theinvention and therefore do not limit its scope, because the inventiveconcepts lend themselves to other equally effective embodiments.

FIG. 1 shows a portion of a frame assembly used to fabricate ananti-fatigue mat.

FIG. 2 shows a portion of the frame assembly with a sheet member inposition thereon.

FIG. 3 shows a complete frame assembly.

FIG. 4 is cross section of the frame assembly of FIG. 3 taken alongsection line 4-4.

FIG. 5 is a cross section of the frame assembly of FIG. 3 taken alongsection line 5-5.

FIG. 6 shows the frame assembly of FIG. 3 at a gel dispensing station.

FIG. 7 shows the frame assembly of FIG. 6 at a gel dispensing stationtaken along section line 7-7.

FIG. 8 shows the frame assembly of FIG. 6 at a gel dispensing stationtaken along section line 8-8.

FIG. 9 shows a vacuum press station for positioning a flexible sheet ona gel layer in the frame assembly.

FIG. 10 shows the vacuum press station of FIG. 9 after the vacuum presspicks up the flexible sheet.

FIG. 11 shows the vacuum press station of FIG. 9 prior to placement ofthe flexible sheet on the gel layer.

FIG. 12 shows the vacuum press station of FIG. 9 after the head isclosed to deposit a flexible sheet on the gel layer in the frameassembly.

FIG. 13 shows the vacuum press station of FIG. 9 when the head isreopened after the deposit of a flexible sheet on the gel layer in theframe assembly.

FIG. 14 shows a pre-cooler and main cooler employed in the assembly lineused to fabricate a mat using the disclosed methodology.

FIG. 15 shows the uncut mat after removal from the frame assembly.

FIG. 16A is a cross section of the uncut mat taken along section line16A-16A of FIG. 15 in an embodiment that employs a vinyl strip topromote the adherence of the sheets forming the mat together.

FIG. 16B is a cross section of the uncut mat taken along section line16A-16A of FIG. 15 in an embodiment that employs a direct RF weld toconnect the sheets forming the mat together.

FIG. 17A is a perspective view of a lower jig used to retain the uncutmat.

FIG. 17A is a cross section of the lower jig of FIG. 17A taken alongsection line 17B-17B that includes a corresponding cross section of theuncut mat that is about to be placed therein.

FIG. 18A is a perspective view of the lower jig with the uncut mattherein shown with a flexible sheet thereon.

FIG. 18B is a cross section of the uncut mat and lower jig taken alongsection line 18B-18B of FIG. 18A.

FIG. 19A is a perspective view of the complete jig with the uncut mattherein.

FIG. 19B is a cross section of the complete jig and uncut mat takenalong section line 19B-19B of FIG. 19A.

FIG. 20 is a perspective view of the uncut mat after RF welding andremoval from the complete jig.

FIG. 21 is a representation of the RF welding station used to create theRF weld of FIG. 20.

FIG. 22 is a representation of a cutting station used in the assemblyline to fabricate the mat.

FIG. 23 is a perspective view of the mat after cutting the mat at itsperiphery to remove excess material.

FIG. 24A is a cross section of the trimmed or cut mat of FIG. 23 takenalong section line 24A-24A showing a vinyl layer used to promoteconnection between the sheets of the mat.

FIG. 24B is a cross section of the trimmed or cut mat of FIG. 23 takenalong section line 24A-24A wherein the sheets of the mat are directlyconnected together without an intervening vinyl strip.

FIG. 25 is a flowchart describing representative steps employed in thedisclosed mat fabrication methodology.

FIG. 26A is a cross section of the completed mat showing a layer nearthe peripheral edge of the sheets of the mat to promote coupling of thesheets together adjacent the peripheral edge.

FIG. 26B is a cross section of the completed mat showing the peripheraledges of the sheet of the mat directly connected to one another.

FIG. 26C is a cross section of the completed mat in the normal useposition.

FIG. 27A is a cross section of another embodiment of the disclosed matthat employs an intermediate buffer sheet or layer.

FIG. 27B is a cross section of the mat of FIG. 27A together with a coldplate for removing heat during mat fabrication.

FIG. 27C is a cross section of the mat of FIG. 27A ready for RF welding.

FIG. 27D is a cross section of the mat of FIG. 27A ready for stitchingat its peripheral edge.

FIG. 27E is a cross section of the mat of FIG. 27C shown in a lower jigof an RF welder.

FIG. 27F is a cross section of the mat of FIG. 27E shown position in anRF welder including both a lower jig and an upper jig.

FIG. 28A-FIG. 28G show cross sections of another embodiment of thedisclosed mat during fabrication of the mat wherein the mat includes aresilient layer, such as a gel layer, that exhibits a first durometerand a barrier layer that exhibits a second durometer.

FIG. 29A-FIG. 29F show cross sections of another embodiment of thedisclosed mat during fabrication of the mat wherein the mat includes alayer, such as a resilient gel layer, that exhibits a first durometerand base sheet that exhibits a second durometer.

FIG. 30A-30B summarize embodiments of the disclosed mat wherein thebarrier layer exhibits the second durometer.

FIG. 31A-31B summarize embodiments of the disclosed mat wherein the basesheet exhibits the second durometer.

DETAILED DESCRIPTION

FIG. 1 shows a portion of a frame assembly 100 that the disclosedmethodology employs to fabricate a mat filled with resilient material.In one embodiment, the resilient material is a viscoelastic polymermaterial such as a synthetic rubber-based gel, a polyurethane-based gelor a silicon-based gel. Frame assembly 100 includes a base frame member105 that is fabricated of metal such as aluminum for example. Frameassembly 100 also includes a central frame member 110 that is spacedapart from base frame member 105 by spacers 115. In one embodiment,spacers 115 are fabricated of Teflon™ material. (Teflon is a trademarkof DuPont.) Spacers 115 space base frame member 105 and central framemember 110 sufficiently far apart to allow cooling air to flow in thespace or channel between these members. In this manner, convectivecooling may be provided to a mat fabricated in the frame assembly aslater described in more detail. Other cooling apparatus such as liquidcooling apparatus may be used in place of the convective coolingapparatus described above.

Central frame member 110 includes registration marks 120 that are usedto register a support sheet in a step of the disclosed method. Moreparticularly, turning to FIG. 2, a flexible support sheet 205 isregistered or aligned with registration marks 120 as shown. In oneembodiment, the support sheet 205 forms the side of the mat that facesthe user while in use on a floor or other surface. The support sheet 205contrasts with the base sheet of the mat (not shown in this view),namely the opposite side of the mat which faces the floor or othersurface while the mat is in use. In this particular embodiment of thedisclosed method, the mat is fabricated in an inverted orientation,namely with the support sheet 205 being placed lowermost in assembly 100and the base sheet being placed uppermost in the assembly as shownbelow. However, this order may be reversed if desired.

Assembly 100 also includes an aperture frame member 210 having anaperture 215 therein. Aperture frame member 210 is mechanicallyrotatably coupled to central frame member 110 by a hinge 220 as shown.FIG. 2 shows assembly 100 in the open position with support sheet 205registered in position on central frame member 110. Once support sheet205 is so registered, aperture frame member 210 is rotated from the openposition to the closed position in the direction indicated by arrow 225.Aperture frame member 210 includes screw holes 230A that align withthreaded screw holes 230B in central frame member 110 when the apertureframe member 210 is closed. The aperture 215 typically exhibits the samegeometry as the desired geometry of the mat being fabricated. In otherwords, if a rectangular, square, circular or elliptical mat is beingfabricated, then aperture 215 exhibits a rectangular, square, circularor elliptical geometry, respectively. The frame members 105,110 and 210may also exhibit the same geometry as aperture 215 although suchstructures are larger than aperture 215. While in one embodiment, framemembers 105,110 and 210 are fabricated of aluminum, it is also possibleto fabricate the frame members from silicon, steel and other durablematerials.

FIG. 3 shows a frame/mat structure 300 that includes frame assembly 100in the closed position with support sheet 205 retained therein. Withframe assembly 100 so closed, holes 230A align with screw holes 230B.Screws 305 are placed in holes 230A and threaded into correspondingthreaded holes 230B. Screws 305 are tightened into threaded holes 230Buntil frame assembly 100 snugly holds support sheet 205 in place. In oneembodiment, the four inner edges 210A, 210B, 210C and 210D of apertureframe member 210 are angled inward to provide a non-trip feature to themanufactured mat as described below in more detail. In this particularexample, an angle of 45 degrees is used for inner edges 210A, 210B, 210Cand 210D with respect to the major plane of aperture frame member 210.Angles smaller or larger than 45 degrees may also be used depending onthe particular application. Frame assembly 100 together with supportsheet 205 forms a gel-receiving cavity 310 as described in more detailbelow.

FIG. 4 is a cross section of the frame/mat structure 300 of FIG. 3 takenalong section line 4-4 of FIG. 3. FIG. 4 shows gel-receiving cavity 310prior to injection of liquid gel therein. FIG. 5 is another crosssection of frame/mat structure 300 of FIG. 3 except taken along sectionline 5-5 of FIG. 3.

FIG. 6 shows a work station 600 as a portion of an assembly line 602 inwhich a mat is fabricated according to the disclosed methodology. Theparticular view of workstation 600 shown in FIG. 6 shows frame/matstructure 300 prior to dispensing gel into the gel receiving cavity 310.Workstation 600 includes a conveyer belt 605 upon which frame/matstructure 300 is situated before liquid gel is dispensed therein. In oneembodiment, gel is supplied to a heater 610 that heats the gel to atemperature at which the gel melts and becomes liquid, for exampleapproximately 410° F. in one embodiment. It may also be possible tosupply liquid gel to gel receiving cavity 310 without heating the gel ifthe gel is liquid at ambient or room temperature, for exampleapproximately 75° in one embodiment. In such an embodiment the gel wouldbe designed to cure over time into a gel layer exhibiting a desireddurometer or softness. A hose 615 supplies liquid gel from heater 610 toa dispenser head 620 that is situated above conveyer belt 605 onassembly line 602. To fill cavity 310 with liquid gel, a controller (notshown) instructs conveyer belt 605 to move in the direction indicated byarrows 625. As cavity 310 passes below dispenser head 620, dispenserhead 620 dispenses heated liquid gel into cavity 620 so that cavity 620is filled with gel before frame/mat structure 300 exits dispenser head620. The controller (not shown) may be programmed to instruct dispenserhead 620 to commence dispensing gel when cavity 310 starts to pass belowdispensing head 620 and to cease dispensing gel slightly before cavity310 exits dispensing head 620.

FIG. 7 shows a cross section of frame/mat structure 300 taken alongsection line 7-7 of FIG. 6 after liquid gel 705 is dispensed into cavity310. A criss-cross hatching denotes gel 705 in cavity 310 in FIG. 7. Theouter edge 705A of gel layer 705 exhibits an angle of 45 degrees toprovide the anti-trip feature mentioned above. As mentioned above, otherangles may also produce acceptable results. FIG. 8 shows a similar crosssection of frame/mat structure 300 except this cross section is takenalong a different section line 8-8 of FIG. 6.

FIG. 9 shows a perspective view of another portion of the assembly line602 including a pressing station 905. This view illustrates pressingstation 905 prior to the arrival of sheet/mat structure 300 so that thepreparation of a flexible base sheet 920 may be seen. Pressing station905 includes a registration panel 910 fabricated from a solid materialsuch as wood or metal. Registration panel 910 rotates or swings fromside to side about a pivot 915. An operator or automated equipmentplaces and aligns a base sheet 920 between registration marks 925. Inone embodiment, when fabrication of the mat is complete, base sheet 920becomes the surface of the mat that faces the floor or other surface onwhich the mat is used. In one embodiment, base sheet 920 is actuallyplaced on registration panel 910 when registration panel 910 is swunginto position on a worktable 930. Then when registration of base sheet920 between registration marks 925 is complete, panel 910 is swung fromits position atop worktable 930 to a location under vacuum press 935 asshown in FIG. 9.

Press 935 includes a head 940 with a flat surface 940A that is capableof holding a sheet of material such as base sheet 920 thereto undervacuum. A vacuum hose 945 connects to press 935 to provide partialvacuum to head 940. When the registered base sheet 920 is in positionbelow press head 940 as shown in FIG. 9, an operator or automatedcontroller rotates press head 940 downward as indicated by arrow 950until the press head contacts base sheet 920. Base sheet 920 is thenheld to press head 940 by the partial vacuum.

FIG. 10 shows that base sheet 920 adheres to press head 940 via vacuumaction when press 920 is opened as indicated by the direction of arrow955. With base sheet 920 so positioned on press head 940, registrationpanel 910 is rotated or otherwise moved to table 930 to leave pressstation 905 clear to receive frame assembly 700. FIG. 10 showsregistration panel 910 prior to being moved to table 930.

FIG. 11 shows frame/mat structure 300 after being moved into positionbelow press head 940 on assembly line 602. Frame/mat structure 300 isfilled with liquid gel as depicted in FIGS. 7 and 8. With frame/matstructure 300 and base sheet 920 so positioned, an operator orprogrammable controller closes press head 940 onto frame/mat structure300 as shown in FIG. 12. To assure that air bubbles are not trapped inthe liquid gel, when press head 940 is closed an operator orprogrammable controller first applies pressure to one end 940B of presshead 940 and then continues applying pressure across press head 940until ending with the application of pressure at end 940C. Press 935 isconfigured such that press head 940 holds base sheet 920 (not visible inFIG. 12) in registration with support sheet 205 (also not visible inFIG. 12). In other words, press head 935 assures that base sheet 920aligns with support sheet 205 when press head 935 deposits base sheet920 on frame/mat structure 300.

FIG. 13 shows press 935 after it has been opened to reveal the frame/matstructure 1300 formed by base sheet 920 and frame/mat structure 300 onwhich base sheet 920 now rests. Gel layer 705 is shown in dotted linesto indicate that gel layer 705 is below base sheet 920 in thisparticular view. As seen in FIG. 13, base sheet 920 overlaps the edgesof gel layer 705 to provide a margin or periphery region which will beattached to a similar margin of support sheet 205. Press 935 thusfunctions to place base sheet 920 on gel layer 705 and support sheet 205therebelow in a vertically aligned manner. Instead of using press 935for this purpose, it may also be possible to employ a roller to roll ona sheet such as sheet 920.

Returning to FIG. 10, it is seen that a pre-cooler 1305 is the next workstation of the assembly line 602 after pressing station 905. After press935 presses base sheet 920 to frame/mat structure 300 to form frame/matstructure 1300, frame/mat structure 1300 moves down the assembly lineand enters pre-cooler 1305. In one embodiment, pre-cooler 1305 chillsassembly 1300 at an air temperature of approximately 50° F. forapproximately 3 minutes. Different temperatures and times can be useddepending upon the particular application.

FIG. 14 shows frame/mat structure 1300 after an operator or programmedcontroller moves frame/mat structure 1300 down the assembly line 602from pre-cooler 1305 to a position under a main cooler 1405 that acts asa main cooling station in the line. In one embodiment, main cooler 1405includes a pneumatic driven press plate 1410. A coolant receiving vesselor chamber 1415 is situated on press plate 1410. In one embodiment,chamber 1415 is filled with ice to maintain the temperature of the pressplate at 32 degrees F. In another embodiment, chamber 1415 is replacedwith coolant carrying pipes in which a liquid such as alcohol flows tomaintain the temperature of press plate 1410 at temperatures lower than32 degrees F.

Before frame/mat structure 1300 enters main cooler 1405, a controller1420 instructs press plate 1410 to raise up a sufficient verticaldistance to allow frame/mat structure 1300 to enter the space underpress plate 1410. With frame/mat structure 1300 so positioned under maincooler 1405, controller 1420 instructs press plate 1410 to move downwardto apply cooling pressure to frame/mat structure 1300. In a mannersimilar to that discussed with reference to FIG. 12, press plate 1410first applies pressure to assembly 1300 at plate end 1410A and thencontinues to apply pressure along press plate 1410 along its lengthuntil pressure is applied at plate end 1410B. In one embodiment,frame/mat structure 1300 remains in main cooler 1405 for approximately 2minutes. Frame/mat structure 1300 may remain in main cooler 1405 forless or more time depending upon the particular application.

Frame/mat structure 1300 next exits main cooler 1405. An operator ormachine under program control removes screws 305 (shown above in FIG.13) from aperture frame member 210. Aperture frame member 210 is thenremoved from the remainder of the assembly. This allows the uncut matformed by support sheet 205, gel layer 705 and base sheet 920 to beeasily removed from central frame member 110. As seen in FIG. 15, sincethe mat is uncut around its peripheral edges 1500A, 1500B, 1500C and1500D, the mat is referred to as uncut mat 1500 at this point in thefabrication process. The rightmost end of uncut mat 1500 is flared opento show gel layer 705 between support sheet 205 and base sheet 920. Itis noted that the mat is still inverted at this point in the fabricationprocess with support sheet 205 on the bottom and base sheet 920 on top.

As part of the process for completing uncut mat 1500, support sheet 205and base sheet 920 are connected to one another along the 4 edges 1500A,1500B, 1500C and 1500D. In one embodiment, wherein both support sheet205 and base sheet 920 are fabricated from a resilient material such asvinyl, 4 strips of like material, namely vinyl in this case, arepositioned around the periphery of uncut mat 1500. FIG. 15 shows these 4strips as vinyl strips 1505A, 1505B, 1505C and 1505D which arerespectively positioned adjacent edges 1500A, 1500B, 1500C and 1500D asshown. These vinyl strips are positioned between support sheet 205 andbase sheet 920 to facilitate the adherence of support sheet 205 to basesheet 920 along the edges of the mat. The vinyl strips 1500A-1500D maybe manually positioned at the locations shown in FIG. 15. Alternatively,support sheet 205 may be prefabricated with the vinyl strips alreadypresent thereon prior to beginning the fabrication process. In yetanother embodiment, base sheet 920 may be prefabricated with the vinylstrips already present thereon prior to the start of the mat fabricationprocess. In one embodiment, support sheet 205 includes a decorativefabric to improve the appearance of the mat. For example, a syntheticleather material may be bonded to a fabric backing material to formflexible support sheet 205. When the user stands on the mat, the supportsheet 205 is oriented upward so that the decorative fabric is visible tothe user. Support sheet 205 may thus provide a cosmetically appealingsurface. Flexible base sheet 920 faces downward toward the floor orother usage surface. Base sheet 920 is intended to provide a highfriction or non-slip surface so that when placed on the floor, the matis stable and does not slide during use. One material that may beemployed for base sheet 920 is a high friction vinyl or urethanelaminated to a fabric backing.

FIG. 16A shows a cross section of uncut mat 1500 taken along sectionline 16A-16A of FIG. 15. Gel layer 705 is sandwiched between supportsheet 205 and base sheet 920. Vinyl strips 1505C and 1505A are alsovisible in the cross section of FIG. 16A. In a subsequent process step,vinyl strips 1505A-1505D will be melted by a radio frequency (RF) welderto cause support sheet 205 to bond with base sheet 920. In anotherapproach depicted in FIG. 16B, the vinyl strips 1505A-1505D are omittedso that peripheral edges of support sheet 205 directly contact theperipheral edges of base sheet 920 prior to placement in the RF welder.In this manner, support sheet 205 and base sheet 920 are directly RFwelded together around their respective peripheral edges. In yet anotherembodiment, the vinyl strips 1505 are replaced with an adhesive, such ashot melt or Epoxy, that causes support sheet 205 to adhere to base sheet920 around the periphery of uncut mat 1500. (Epoxy is a trademark of TheDow Chemical Company.)

Returning now to FIG. 16A, vinyl strips 1500A-1500D are positioned asshown and described above. Uncut mat 1500 is next placed in a lower jig1700 that is illustrated in FIG. 17A. More particularly, after stripplacement, uncut mat 1500 is positioned in lower jig 1700 as indicatedin FIG. 17B. FIG. 17B is a cross section of lower jig 1700 and uncut mat1500 as uncut mat 1500 is oriented for placement in lower jig 1700. Thecross section of lower jig 1700 depicted in FIG. 17B is taken alongsection line 17B-17B of FIG. 17A. Lower jig 1700 exhibits geometrysimilar to the geometry of uncut mat 1500. For example, if mat 1500 isrectangular, square, circular or elliptical, then lower jig 1700 iscorrespondingly rectangular, square, circular or elliptical. Lower jig1700 includes a raised portion 1705 that acts as a funnel for RF energywhen lower jig 1700 and uncut mat 1500 are later placed in the RFwelder. FIG. 17B shows uncut mat 1500 in the inverted position andpositioned above lower jig 1700 immediately before uncut mat 1500 isplaced in lower jig 1700. It is noted that raised portions 1705 of lowerjig 1700 include angled surfaces 1710 extending adjacent the innerperimeter of raised portions 1705. Raised portions 1710 receive and matewith the angled surface of support sheet 205 as shown. Support sheet 205follows the angled contours of gel layer 705 and angled surfaces 1710.

FIG. 18A shows uncut mat 1500 fully placed in lower jig 1700 prior tobeing moved into the RF welder. The raised portion 1705 of lower jig1700 is shown in dotted lines below uncut mat 1500. FIG. 18B is a crosssection of lower jig 1700 and uncut mat 1500 of FIG. 18A taken alongsection line 18B-18B.

FIG. 19A shows an upper jig 1905 situated above lower jig 1700 and uncutmat 1500 to form a completed jig assembly 1900. FIG. 19B is a crosssection of jig assembly 1900 of FIG. 19A taken along section line19B-19B. Upper jig 1905 includes a raised portion 1910 that verticallyaligns with raised portion 1705 of lower jig 1700. With raised portionsof upper jig 1905 and lower jig 1700 so aligned, assembly 1900 is placedin an RF welding chamber or station (not shown). When the RF weldingstation is activated, RF energy is directed between the raised portions1910 of upper jig 1905 and the raised portions 1705 of lower jig 1700,thus melting vinyl strips such as strip 1505C seen in FIG. 19B. Thiscauses the edges of uncut mat 1500 to be welded together at weldedregion 1915 as seen in dotted line in FIG. 19A. The inner boundary 1915Aand outer boundary 1915B of welded region 1915 are indicated by thedotted lines. After completion of RF welding, upper jig 1905 is raisedand the welded uncut mat is removed from lower jig 1700. Alternatively,the edges of the uncut mat could be welded together without a jig byusing ultrasonic welding. Ultrasonic welding may be particularlyapplicable the larger the size of the mat becomes or for mats withirregular shapes.

FIG. 20 is a perspective view of the uncut mat after RF welding. Once RFwelding is complete and removed from the jig, the uncut mat isdesignated as uncut mat 2000. FIG. 20 shows the welded region 1915 indotted lines extending around the peripheral edge of uncut mat 2000. Itis noted that in FIG. 20, the mat is no longer in the invertedorientation, but rather is in the normal orientation ready for use. FIG.21 is a representation of the RF welder unit or station 2105 in whichuncut mat 1500 was welded to become uncut mat 2000.

When RF welding is complete, uncut mat 2000 is moved to a cuttingstation 2205 shown in FIG. 22. In one embodiment, a cut is made aroundthe edge of uncut mat 2000 such that approximately ½ of the width of thewelded region 1915 is removed. In other embodiments, more than or lessthan ½ the width of the welded region may be removed depending upon theparticular application. FIG. 23 shows the resultant cut mat 2300. Theinner boundary 1915A of welded region 1915 remains and is shown indotted line.

FIG. 24A shows a cross section of cut mat 2300 taken along section line24A-24A of FIG. 23. More particularly, FIG. 24A shows the embodimentwherein vinyl strip 1505 is situated adjacent gel layer 705 and betweenbase sheet 920 and support sheet 205. In the RF welding process, vinylstrip 1505 melts around the mat's periphery thus causing the edge of thebase sheet 920 and support sheet 205 to adhere to one another. FIG. 24Bshows the same cross section of cut mat 2300 except in the embodimentwherein placement of vinyl strip 1505 is omitted such that base sheet920 and support sheet 205 bond directly to one another when placed inthe RF welder. In yet another embodiment, an adhesive such as hot meltor Epoxy may be substituted for the vinyl strip 1550 around theperiphery of the mat and the RF welding operation may be omitted. Inthis embodiment, the adhesive seals base sheet 920 to support sheet 205around the periphery of the mat.

FIG. 25 is a flowchart that shows one embodiment of the disclosedmethodology for fabricating a resilient mat. In this particularembodiment, the mat is fabricated with an inverted orientation with thesupport sheet 205 (on which the user stands or otherwise contacts) onthe bottom and the base sheet 920 (which faces the floor or othersurface) on top in the frame assembly. However, in another embodiment,this order is reversed such that the mat is fabricated in a normalorientation with base sheet 920 on the bottom and the support sheet 205on the top in the frame assembly.

Process flow commences with start block 2500. The gel is prepared byheating gel to a temperature of approximately 380 degrees F. in oneembodiment, as per block 2505. More information regarding preparation ofgel 705 is included below in the flowchart of FIG. 26. The apertureframe member 210 is then opened either manually or by a processcontroller, as per block 2510. An operator or process controller thenregisters support sheet 205 on central frame member 110, as per block2515. Once support sheet 205 is registered, aperture frame member 210 isclosed. Screws are then used to secure aperture frame member 210 tocentral frame member 110, as per block 2520. Liquid gel 705 is thendispensed into the gel receiving cavity 310 in the frame/mat structureformed by support sheet 205, central frame member 110, aperture framemember 210 and base frame member 105, as per block 2525.

The base sheet 920 is now prepared for positioning on gel layer 705.Base sheet 920 is registered on registration panel 910, as per block2530. The head 940 of vacuum press 935 then swings downward and contactsbase sheet 920. Vacuum is then applied to head 940 such that head 940captures base sheet 920 thereon in registered fashion, as per block2535. Head 940 with base sheet 920 thereon now swings upward to clearthe workspace at vacuum press 935, as per block 2540. The assemblyformed by base frame member 105, central frame member 110, spacers 115,aperture frame member 210 and gel layer 705 is then moved into positionbelow head 940 of the vacuum press. The head 940 of the vacuum pressthen swings downward such that base sheet 920 contacts gel layer 705 andaperture frame member 210, as per block 2555. The vacuum is released inhead 940 and head 940 swings upward leaving base sheet member 920 atopgel layer 705 and vertically aligned with support sheet 205 below, asper block 2560. In other words, base sheet 920 is registered withrespect to support sheet 205 when base sheet 920 is deposited on gellayer 705 by vacuum press 935.

The frame/mat structure formed by base sheet 920, support sheet 205, gellayer 705 and the frame members is then moved into pre-cooler 1305 toreduce the temperature of the frame/mat structure, as per block 2565.The frame/mat structure is then moved along the assembly line to maincooler 1405 to further reduce the temperature of the frame/matstructure, as per block 2570. At the main cooler, a cold plate contactsthe frame/mat structure. First pressure the cold plate applies pressureto one end of the frame/mat structure. The cold plate then appliespressure across the frame/mat structure until reaching the opposite endof the frame/mat structure, as per block 2575. After cooling, theframe/mat structure is removed from main cooler 1405, as per block 2580.Next, screws 305 are removed to allow the opening of aperture framemember 210, as per block 2585. The uncut mat is then removed from theframe, as per block 2590. Vinyl strips 1505 are then applied around theperiphery of the uncut mat between support sheet 205 and base sheet 920,as per block 2591. Vinyl strips 1505 are positioned adjacent theoutermost portion of gel layer 705 near the periphery of the uncut mat.

The uncut mat with vinyl strips 1505 is then placed in lower jig 1700,as per block 2592. Next, upper jig 1905 is positioned above the uncutmat and lower jig 1700 in preparation for RF welding, as per block 2593.The jig containing the uncut mat is then moved to RF welder 2105, as perblock 2594. RF welder 2150 then conducts an RF welding operation thatmelts the adhesive strips 1505 thus causing support sheet 205 and basesheet 920 to adhere to one another, as per block 2595. The welded butstill uncut mat is then removed from RF welder 2150, as per block 2596.Next, the mat is cut in the welded region to trim away superfluous edgematerial, as per block 2597. The mat is now complete and the fabricationprocess ends at end block 2598.

Gel layer 705 provides a very pleasing feel when the user steps on thefully assembled mat. This is especially true when the user steps on themat without wearing shoes. In one embodiment, the durometer or softnessof gel layer 705 should be sufficiently high that it is comfortable forthe user to step on the mat and yet sufficiently firm that the user isstable when standing on the mat. Stability here refers to the avoidanceof undue lateral motion when standing on the mat. Thus, in oneembodiment, the durometer of gel layer 705 is selected to be 50 on theShore A scale with a tolerance of approximately minus 5 andapproximately plus 2. Durometers greater or less than this range canalso be used depending on the particular user application. In oneembodiment, gel layer 705 may be formed of any synthetic rubber materialthat includes thermoplastic rubber and mineral oil provided that thedurometer of gel layer 205 is as described above. Gel may be stored insemi-solid form prior to placement in heater 610 of FIG. 6. In oneembodiment, heater 610 provides heated liquid gel to assembly 300. Gelis provided to assembly 310 in liquid form so that the gel can take theform of gel receiving cavity 310 while the mat is being fabricated.

In one embodiment shown in FIG. 26A, a buffer layer 2605 of polyurethaneis sprayed or otherwise applied to the inner side of support sheet 205that faces gel layer 705. Another buffer layer 2610 is similarly appliedto the inner side of base sheet 920 that faces gel layer 705. In actualpractice, buffer layers 2605 and 2610 are applied to support sheet 205and base sheet 920 prior to placing these sheets in the frame assembly.Buffer layers 2605 and 2610 perform one or both of the following twofunctions. Buffer layers 2605 and 2610 prevent mineral oil in gel layer705 from undesirably migrating from gel layer 705 through the base sheetor support sheet to the exterior of the mat. Buffer layers 2605 and 2610may also allow gel layer 705 to move within the mat so that, when themat is rolled up and then later unrolled, a smoother mat is achieved.FIG. 26B shows the same buffer layers 2605 and 2610 in the embodiment ofthe mat wherein the outer edge of support sheet 205 and base sheet 920are directly RF welded to one another without the use of intermediatevinyl strips 1505.

While FIG. 26A shows a cross section of the completed mat 2600 in theinverted orientation in which the mat was fabricated, FIG. 26C shows thesame mat 2600 that has been rotated 180 degrees to the normal useorientation. In the normal user orientation, base sheet 920 is on thebottom of the mat and support sheet 205 is on the top side of the mat.Angled surface 205A of support sheet 205 provides the anti-trip featurementioned above. The angling of surface 205A makes it less likely that auser will trip on an edge of the mat than if the edge of the mat wereperpendicular.

In an alternative embodiment, rather than spraying or applying bufferlayers 2605 and 2610 as described above, an intermediate sheet or buffersheet 2705 is positioned on gel layer 705 prior to installation of basesheet 920 on the mat. For example, rather than using press 940 toposition base sheet 920 on liquid gel layer 705, press 940 may positiona buffer sheet 2705 on gel layer 705 to form the partially assembled mat2700 depicted in FIG. 27A. In one embodiment, buffer sheet 2705 coversgel layer 705, but does not extend into the margin 2710 adjacent theperipheral edge of the mat. Buffer sheet 2705 is fabricated from amaterial that slides easily with low friction with respect to base sheet920 that is placed on buffer sheet 2705 in a subsequent step. However,prior to placement of base sheet 920 on the mat assembly, a cold platecooler 2715 may be placed on the mat assembly as shown in FIG. 27B tocool and remove heat from the mat assembly. Cold plate cooler 2715 mayinclude cooling channels 2720 in which a convective gas coolant such asair or a liquid coolant such as alcohol flows. After cooling the matassembly to the ambient or room temperature, for example approximately75° F., the cold plate 2715 is removed from the mat assembly.

FIG. 27C shows mat assembly 2700 after base sheet 920 is situatedthereon. Base sheet 920 may be attached to support sheet 205 at margin2710 directly by RF welding in a manner similar to that depicted in FIG.26B or indirectly via a vinyl strip as shown in FIG. 26A. Alternatively,the peripheral edge of support sheet 205 may be adhesively coupled tothe peripheral edge of base sheet 920 at margin 2710. In yet anotherembodiment, the peripheral edge of support sheet 205 may be sewn orstitched to the peripheral edge of base sheet 920 at margin 2710 toconnect the two sheets together. As depicted in FIG. 27C, the matassembly is still in the inverted position rather that the orientationthat the user actually employs.

FIG. 27D shows another embodiment of the mat assembly wherein a sewnperipheral edge holds support sheet 205 and base sheet 920 together toform mat assembly 2750. In this particular sewn embodiment, a wraparoundflap 2725 is positioned at the outer edge of mat assembly 2750 as shownin FIG. 27D. The mat assembly is then sewn or stitched at margin 2710through upper flap 2725A, base sheet 920, support sheet 205 and lowerflap 2725B to hold the assembly together.

As mentioned above, buffer sheet 2705 is fabricated from a material thatslides with respect to base sheet 920 that is placed on buffer sheet2705. However, buffer sheet 2705 adheres to gel layer 705. One materialthat is suitable for buffer sheet 2705 is a fabric such as a cotton orNylon sheet, for example. Such a material adheres to the gel but allowsthe base sheet 920 to move with respect to buffer sheet 2705 and the gellayer 705 attached to buffer sheet 2705. A pocket of air (not shown) mayexist between buffer sheet 2705 and base sheet 920.

By allowing base sheet 920 to move with relatively low friction withrespect to gel layer 705, buffer sheet 2705 may prevent wrinkling of themat assembly when the mat assembly is rolled up for shipment and thenunrolled for actual use. Buffer sheet 2705 may also form a barrier thatreduces migration of liquid contained in gel layer 705. For example, ifgel layer 705 contains any oils that may separate from the gel overtime, then buffer sheet 2705 acts as a barrier that stops or reduces theflow of such liquids to the base sheet 920 of the mat.

Positioning buffer sheet 2705 on gel layer 705 as shown in FIG. 27A andFIG. 27B, allows cold plate 2715 to quickly draw heat out of the heatedgel layer 705. This speeds up the manufacturing process. Moreover,buffer sheet 2705 prevents cold plate 2715 from sticking to gel layer705 which could otherwise damage the mat assembly. In one embodiment,cold plate 2715 is applied to the mat assembly of FIG. 27B immediatelyafter application of buffer sheet 2705 to gel layer 705 to remove heattherefrom prior to installing base sheet 920 on the mat assembly. In oneembodiment, when heat is so removed from the mat assembly, thepreviously liquid gel layer 705 becomes semi-solid.

As described above with respect to FIG. 27C, RF welding may be employedto hold mat 2700 together at margin 2710. More particularly, RF weldingforms a weld that bonds support sheet 205 to base sheet 920 at margin2710. One RF welding apparatus that may be used to weld these componentstogether is lower jig 1700 of FIG. 17A, 17B and upper jig 1905 of FIG.19A, 19B. FIG. 27E-FIG. 27F, taken together, show an alternative jig forRF welding support sheet 205 to base sheet 920 in the embodiment thatincludes buffer sheet 2705. More particularly, FIG. 27E shows matassembly 2700 situated in lower jig 1700, namely the same lower jigdepicted in FIG. 17A, 17B. However, FIG. 27F shows mat assembly 2700with a different upper jig 2760 than upper jig 1905 of FIG. 19A, 19B.Whereas upper jig 1905 includes protrusions 1910 to help direct the RFenergy employed in the RF welding process, upper jig 2760 of FIG. 27Fexhibits a flat surface 2760A that contacts support sheet 920. Whenupper jig 2760 is moved and pressed into contact with mat assembly 2700,the flat surface 2760A helps reduce wrinkling in the mat. The raisedportions 1705 of lower jig 1700 assure that the RF welding energy flowsthrough support sheet 205 and base sheet 920 at margin 2710 to form theRF weld at that location as desired.

It may be desirable to provide mats with different feels to the user fordifferent applications. For example, in some applications it may bedesirable for the mat to exhibit a sturdy or more firm feeling to theuser standing on the mat. In other applications, it may be desirable toprovide the user with a softer feel while standing on the mat. FIGS.28A-28G show process steps in fabricating a mat 2800 that exhibitsmultiple durometers, namely one layer of the mat exhibits apredetermined durometer and another layer of the mat exhibits adifferent durometer. Durometer is a measure of the stiffness, resilienceor rigidity of a material. The mat fabrication process that FIGS.28A-28G depict is similar to the process that FIGS. 27A-27F depict.However, in the process of FIGS. 28A-28G, buffer sheet 2705 exhibits adurometer different from the durometer of layer 705. Buffer sheet 2705is also referred to as a barrier sheet or layer. Like numbers indicatelike elements when comparing the structures of FIG. 28A-28G with thestructures of FIG. 27A-27F.

FIG. 28G shows completed mat 2800 after removal from jigs 1700, 2760 ofFIG. 28F. In FIG. 28G, completed mat 2800 is rotated into the normal useposition, namely with flexible support sheet 205 facing upward towardthe user and flexible base sheet 920 facing downward toward the floor orother surface on which the mat is used. Layer 705 exhibits a firstdurometer (durometer 1) and layer 2705 exhibits a second durometer(durometer 2) that is different from the first durometer. In oneembodiment, layer 2705 exhibits a durometer greater than the durometerof layer 705. Layer 2705 may be a foam material such as polyurethanefoam with a durometer greater than the durometer of layer 705 which maybe a gel layer. For example, in one embodiment, foam layer 2705 mayexhibit a durometer of approx. 55-approx. 75 on the OO Shore scale whilegel layer 705 exhibits a durometer of approx. 15-approx. 30 on the OOShore scale. These Shore values are provided for purposes of example andshould not be regarded as limiting. Other durometer values outside ofthese ranges may produce acceptable results depending on the particularapplication. As stated above, in this embodiment, the durometer ofbuffer or barrier layer 2705 is greater than the durometer of layer 705.Stated alternatively, the durometer of layer 705 is less than thedurometer of layer 2705. One application of such a mat 2800 whereinlayer 705 exhibits a lower durometer is an application where the userstanding on the mat prefers a softer feel. In this embodiment, layer2705 acts as both a barrier layer that prevents migration of oil fromgel in layer 705 and also as a second durometer layer. FIG. 28G depictsflexible base sheet as the lowermost layer of mat 2800. When thedurometer of buffer layer 2705 is greater than the durometer of layer705, this provides the resultant mat 2800 with additional structuralintegrity.

In an alternative embodiment, layer 705 exhibits a durometer greaterthan the durometer of layer 2705. Referring again to FIG. 28G, layer 705may be a gel layer that exhibits a higher durometer than buffer orbarrier layer 2705 below. Buffer layer 2705 may be fabricated of lowerdurometer polyurethane foam. In this embodiment, layer 705 may exhibit adurometer of approx. 55-approx 75 on the OO Shore scale while layer 2705exhibits a durometer of approx. 15-approx. 30 on the OO Shore scale.Again, these Shore values are provided for purposes of example andshould not be regarded as limiting. Other durometer values outside ofthese ranges may produce acceptable results depending on the particularapplication. One application of such a mat 2800 wherein layer 705exhibits a durometer greater than the durometer of layer 2705 is instyling salons and other areas where high heel shoes may be worn. Thismat structure lessens the likelihood of puncture and wear damage fromshoes that concentrate weight on a small surface area of the mat. Inthis embodiment, layer 2705 acts as both a barrier layer that preventsmigration of oil from gel in layer 705 and also as a second durometerlayer.

FIGS. 29A-29E depict an embodiment of a mat 2900 that includes a bufferor barrier layer 2705 that is separate and distinct from the first andsecond durometer layers. The mat fabrication steps that FIGS. 29A-29Cdepict are similar to the steps depicted in FIGS. 27A-27C with likenumbers indicating like elements. As seen in FIG. 29C, mat 2900 includesa buffer or barrier layer 2705 that separates gel layer 705 fromflexible base sheet 920. Gel layer 705 exhibits a first durometer(durometer 1), while flexible base sheet 920 exhibits a second durometer(durometer 2). FIG. 29D shows mat 2900 rotated to position for use bythe user, namely with flexible support sheet 205 facing upward towardthe user and flexible base sheet 920 facing downward toward the floor orother base on which the mat is used. In one embodiment, gel layer 705exhibits a first durometer that that is less than the second durometerof flexible base sheet 920. For example, in one embodiment, gel layer705 exhibits a durometer of approx. 15-approx. 30 on the OO Shore scalewhile flexible base sheet 920 may exhibit a durometer of approx.55-approx 75 on the OO Shore scale. In another embodiment, gel layer 705may exhibit a first durometer that is greater than the second durometerof flexible base sheet 920. For example, in one embodiment, gel layer705 may exhibit a durometer of approx. 55-approx 75 on the OO Shorescale while flexible base sheet 920 exhibits a durometer of approx.15-approx. 30 on the OO Shore scale. Again, these durometer values arerepresentative and should not be taking as limiting.

In the mat 2900 embodiment depicted in FIG. 29D, flexible base sheet 920includes an integral high friction or non-slip external surface thatcontacts the floor to prevent slippage. For example, flexible base sheet920 includes rubber-like portions that contact and grip the floor orother surface to lessen or prevent movement on the floor. In thisparticular embodiment, the high friction or non-slip external surface isan integral part of flexible base sheet 920.

FIG. 29E-29F depict another embodiment as mat 2900′ which is similar tomat 2900 except that mat 2900′ includes a layer 2905 of high friction ornon-slip material that is separate from, but attached to, flexible basesheet 920. In other words, in this embodiment, a non-slip surface is notintegral to flexible base sheet 920. Non-slip layer 2905 may be attachedto flexible base sheet 920 by adhesive therebetween. In one embodimentshown in FIG. 29E, after non-slip layer 2905 is attached to flexiblebase sheet 920, the mat assembly is then sewn or stitched at margin 2710through non-slip layer 2905, upper flap 2725A, base sheet 920, supportsheet 205 and lower flap 2725B to hold the assembly together. Theresultant mat 2900′ is then rotated to the in-use position as shown inFIG. 29F.

FIGS. 30A, 30B, 31A and 31B summarize mat embodiments described above.More particularly, FIGS. 30A and 30B respectively show mats 3001 and3002 wherein the barrier layer is the second durometer layer. FIGS. 31Aand 31B respectively show mats 3101 and 3102 wherein the base sheet isthe second durometer layer.

In more detail, FIG. 30A shows mat 3001 wherein barrier layer 2705 isthe second durometer layer. Mat 3001 includes support sheet 205. Mat3001 also includes a layer 705 that exhibits a first durometer(durometer 1) and a barrier layer 2705 that exhibits a second durometer(durometer 2) that is different from the first durometer. The seconddurometer layer 2705 forms a barrier layer that prevents oils, if any,from first durometer layer 705 from reaching base sheet 920. In oneembodiment of mat 3001, the first durometer layer 705 exhibits a lowerdurometer than the second durometer barrier layer 2705. In anotherembodiment of mat 3001, the first durometer layer 705 exhibits a higherdurometer than the second durometer barrier layer 2705. In mat 3001 ofFIG. 30A, base sheet 920 includes an integral non-slip surface toprevent or lessen slippage of mat 3001 on a floor or other surface. FIG.30B shows a mat 3002 that is similar to mat 3001 except that mat 3002includes a non-slip layer 3005 that is separate from base sheet 920 towhich it adheres. The layers of mats 3001 and 3002 may be sewn at theirmargins 2710 or otherwise bonded together as described above.

FIG. 31A shows mat 3101 wherein the base sheet 920 is the seconddurometer layer. Mat 3101 includes support sheet 205. Mat 3101 alsoincludes a layer 705 that exhibits a first durometer (durometer 1) and abarrier layer 2705. Mat 3101 further includes base sheet 920 that actsas a second durometer layer that exhibits a durometer that is differentfrom the first durometer of layer 705. In one embodiment of mat 3101,the first durometer layer 705 exhibits a lower durometer than the seconddurometer base sheet 920. In another embodiment of mat 3101, the firstdurometer layer 705 exhibits a higher durometer than the seconddurometer base sheet 920. In mat 3101 of FIG. 31A, base sheet 920includes an integral non-slip surface to prevent or lessen slippage ofmat 3101 on a floor or other surface. FIG. 31B shows a mat 3102 that issimilar to mat 3101 except that mat 3102 includes a non-slip layer 3105that is separate from base sheet 920 to which it adheres. The layers ofmats 3101 and 3102 may be sewn at their margins 2710 or otherwise bondedtogether as described above.

A methodology for fabricating a resilient mat is thus disclosed in theabove description. The fabricated mat is typically comfortable on whichto stand or otherwise use to support a part of the body. The layers thatexhibit the first and second durometers cooperate to influence the feelof the mat to the user. It should be understood that the steps in thedescribed method need not necessarily be performed in the orderdescribed.

Modifications and alternative embodiments of this invention will beapparent to those skilled in the art in view of this description of theinvention. Accordingly, this description teaches those skilled in theart the manner of carrying out the invention and is to be construed asillustrative only. The forms of the invention shown and describedconstitute the present embodiments. Persons skilled in the art may makevarious changes in the shape, size and arrangement of parts. Forexample, persons skilled in the art may substitute equivalent elementsfor the elements illustrated and described here. Moreover, personsskilled in the art after having the benefit of this description of theinvention may use certain features of the invention independently of theuse of other features, without departing from the scope of theinvention.

1. A method of fabricating an anti-fatigue mat comprising: positioning afirst flexible support sheet on a first frame member; positioning asecond frame member on the first flexible support sheet, the secondframe member including an aperture configured to accept heated liquidgel therein; dispensing the heated liquid gel into the aperture in thesecond frame member so that the heated liquid gel covers a surface ofthe first flexible support sheet exposed by the aperture, the heatedliquid gel exhibiting a first predetermined durometer when cooled; andpositioning a barrier layer on the second frame member and covering theheated liquid gel, the barrier layer exhibiting a second predetermineddurometer, and cooling the liquid gel to form a gel layer exhibiting thefirst predetermined durometer.
 2. The method of claim 1, wherein thefirst predetermined durometer of the gel layer is less than the secondpredetermined durometer of the barrier layer.
 3. The method of claim 1,wherein the first predetermined durometer of the gel layer is greaterthan the second predetermined durometer of the barrier layer.
 4. Themethod of claim 1, wherein the barrier layer comprises foam.
 5. Themethod of claim 1, further comprising positioning a second flexiblesheet on the second frame member and covering the barrier layer.
 6. Themethod of claim 5, further comprising removing the mat assembly formedby the first flexible support sheet, the gel layer, the barrier layerand the second flexible sheet from the frame assembly formed by thefirst and second frame members.
 7. The method of claim 6, furthercomprising attaching the first flexible support sheet to the secondflexible sheet at a periphery of the first flexible sheet and aperiphery of the second flexible sheet.
 8. An anti-fatigue mat,comprising: a first flexible sheet; a resilient gel layer situated onthe first flexible sheet and exhibiting a first predetermined durometer;a flexible barrier layer situated on the resilient gel layer, theflexible barrier layer adhering to the resilient gel layer, the flexiblebarrier layer exhibiting a second predetermined durometer different fromthe first predetermined durometer of the resilient gel layer; and asecond flexible sheet situated on the flexible barrier layer, theflexible barrier layer being moveable with respect to the secondflexible sheet.
 9. The anti-fatigue mat of claim 8 wherein the firstpredetermined durometer of the resilient gel layer is less than thesecond predetermined durometer of the flexible barrier layer.
 10. Theanti-fatigue mat of claim 8 wherein the first predetermined durometer ofthe resilient gel layer is greater than the second predetermineddurometer of the flexible barrier layer.
 11. The anti-fatigue mat ofclaim 8, wherein the first flexible sheet is a support sheet on which auser may stand.
 12. The anti-fatigue mat of claim 8, wherein the secondflexible sheet is a base sheet that includes an integral high frictionsurface for placement on a floor or other surface.
 13. The anti-fatiguemat of claim 8, further comprising a layer of high friction materialthat adheres to the second flexible sheet to lessen slippage of theanti-fatigue mat when in use.
 14. An anti-fatigue mat, comprising: afirst flexible sheet; a resilient gel layer situated on the firstflexible sheet and exhibiting a first predetermined durometer; aflexible barrier layer situated on the resilient gel layer, the flexiblebarrier layer adhering to the resilient gel layer, and a second flexiblesheet situated on the flexible barrier sheet, the flexible barrier sheetbeing moveable with respect to the second flexible sheet, the secondflexible sheet exhibiting a second predetermined durometer differentfrom the first predetermined durometer of the resilient gel layer. 15.The anti-fatigue mat of claim 14, wherein the first predetermineddurometer of the resilient gel layer is less than the secondpredetermined durometer of the second flexible sheet.
 16. Theanti-fatigue mat of claim 13, wherein the first predetermined durometerof the resilient gel layer is greater than the second predetermineddurometer of the second flexible sheet.
 17. The anti-fatigue mat ofclaim 14, wherein the second flexible sheet is a base sheet thatincludes an integral high friction surface for placement on a floor orother surface.
 18. The anti-fatigue mat of claim 14, further comprisinga layer of high friction material attached to the second flexible sheetto lessen slippage of the mat when placed on a floor or other surface.19. The anti-fatigue mat of claim 14, wherein the first flexible sheetis a support sheet on which a user may stand.